The present invention relates to a noise damper for pneumatic tire which is disposed in a tire hollow and secured to a wheel rim.
In recent years, as the mechanical noise from automobiles especially passenger cars is greatly reduced, the tires especially passenger car tires are strongly required to reduce their noise. There are many factors in the tire noise, but a circumferential resonance of the air in the annular tire hollow is a major factor. That is, a ring of air inside the tire continuous around the rim is excited by vibrations during running and resonates in the circumferential direction. Usually, a resonance peak occurs in a frequency range of from 50 to 400 Hz according to the tire size.
In the published Japanese patent JP-B-7-14682, an assembly of a wheel rim and a pneumatic tire mounted thereon is disclosed, wherein a ball-like body which is made of rubber, sponge or the like is put in the annular tire hollow to block the circumferential continuity thereof to control resonance. Such a ball-like body is however, liable to disturb the high-speed rotational balance of the tire because the inner surface of the tire receives a full gravity of the ball-like body which increases as the rotational speed increases. Further, it has a tendency to make it difficult to mount the tire on a wheel rim.
It is therefore, an object of the present invention to provide a noise damper which can control resonance of the tire hollow to reduce tire noise without sacrificing the high-speed balance and rim-mounting operation.
According to the present invention, a tire noise damper is made of a flexible material and comprises a base to be secured to a wheel rim and at least one flap extending from the base to be risen radially outwards from the wheel rim by centrifugal force during running to block the annular tire hollow.
Definitions
xe2x80x9cStandard loaded conditionxe2x80x9d is that the tire is mounted on a standard rim and inflated to a standard pressure, and then loaded with 74% of a standard load.
xe2x80x9cNormally-inflated unloaded conditionxe2x80x9d is that the tire is mounted on the standard rim and inflated to the standard pressure, but loaded with no tire load.
The standard rim is the xe2x80x9cstandard rimxe2x80x9d specified in JATMA, the xe2x80x9cMeasuring Rimxe2x80x9d in ETRTO, the xe2x80x9cDesign Rimxe2x80x9d in TandRA or the like.
The standard pressure is the xe2x80x9cmaximum air pressurexe2x80x9d in JATMA, the xe2x80x9cInflation Pressurexe2x80x9d in ETRTO, the maximum pressure given in the xe2x80x9cTire Load Limits at Various Cold Inflation Pressuresxe2x80x9d table in TandRA or the like. In case of passenger car tires, however, 200 kPa is used as the standard pressure.
The standard load is the xe2x80x9cmaximum load capacityxe2x80x9d in JATMA, the xe2x80x9cLoad Capacityxe2x80x9d in ETRTO, the maximum value given in the above-mentioned table in TandRA or the like.